Plasmonic-3D photonic crystals microchip for surface enhanced Raman spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Plasmonic-dielectric hybrid substrates offer unique optical properties.
• Three-dimensional photonic crystals (3D PCs) provide enhanced light-matter interactions.
• Surface-enhanced Raman spectroscopy (SERS) requires efficient substrates for high sensitivity.

Purpose of the Study:

• To fabricate and characterize novel plasmonic-dielectric hybrid substrates.
• To investigate the SERS performance of these substrates for chemical detection.
• To demonstrate the potential of these substrates in microfluidic devices.

Main Methods:

• Magnetron sputtering of silver (Ag) onto hydrophobized silica 3D photonic crystals.
• Fabrication without etching processes.
• Characterization using SERS to detect adenine.

Main Results:

• Achieved significant Raman enhancement without "hot-spots" like nanogaps.
• Attributed enhancement to enhanced electromagnetic fields, nanoparticle scattering, and slow photon effects.
• Reached a detection limit for adenine at the nM level with an enhancement factor of 1.13 × 10⁷.
• Demonstrated microchip integration enabling micro-detection via superhydrophobic concentration.

Conclusions:

• The developed Ag-islands on 3D photonic crystals exhibit superior SERS performance compared to conventional methods.
• Facile fabrication and high enhancement factors make these substrates promising for chemical sensors, Raman mapping, and bioassays.
• The integration into microchips facilitates sensitive and concentrated micro-detection.